1. Field of the Invention
The present invention relates to a method and an apparatus for stunning of slaughter animals.
2. Description of the Prior Art
In stunning of slaughter pigs some slaughterhouses use a box stunning apparatus with CO2 atmosphere, e.g. an apparatus of the “Backloader” type from Butina ApS, Denmark. Animals are driven along a driveway towards an entrance area, and when a number of animals corresponding to the box size has entered the area it is closed towards the driveway to prevent other animals entering the area. The group of animals in the area is then driven into a box, which is placed in a receiving position at the entrance area. The box is closed and lowered into a pit with CO2. After the animals have been in the CO2 atmosphere for some time they have been stunned and the box is lifted out of the pit to an emptying area opposite the entrance area. The animals are discharged from the box, and shackled for sticking and bleeding.
In box stunning apparatuses of this type movement of a box depends on the movement of the other boxes, because the boxes are conveyed close after one another in a closed path. This means that the movement of the boxes must be stopped each time a box is being filled.
The ability of the apparatus to supply the slaughter line with stunned animals depends to a great extent on the time it takes for a group of animals to pass into the entrance area, the time it takes to separate the group of animals from the animals in the driveway, and the time it takes to drive the group into a box. The time spent on these work phases varies considerably because of the behaviour of the animals. Some animals walk in of their own volition, or are easy to drive in, while others are unwilling or hesitate, so that the process is delayed. To compensate for this, box stunning apparatuses are designed with excess capacity so that the required number of stunned animals can be provided on the emptying side even when process time on the entrance side is prolonged. However, the result of this is that too many animals are supplied to the slaughter line when the process on the entrance side is smooth, or if the operator puts pressure on the animals to gain time in connection with work breaks. The result is a build-up of animals on the emptying side, which means that the operators there and on the rest of the slaughter line cannot manage to process the stunned animals at the speed at which they arrive.